Synthesis of chabazite-containing molecular sieves and their use in the conversion of oxygenates to olefins

ABSTRACT

In a method of synthesizing a silicoaluminophosphate molecular sieve having 90+% CHA framework-type character, a reaction mixture is prepared comprising sources of water, silicon, aluminum, and phosphorus, as well as an organic template. In one aspect, the reaction mixture is heated at more than 10° C./hour to a crystallization temperature and is retained at the crystallization temperature or within the crystallization temperature range for a crystallization time from 16 hours to 350 hours to produce the silicoaluminophosphate molecular sieve. In another aspect, the reaction mixture is heated at less than 10° C./hour to a crystallization temperature from about 150° C. to about 225° C. and is then retained there for less than 10 hours to produce the silicoaluminophosphate molecular sieve. The molecular sieve can then be recovered from the reaction mixture and, preferably, used in a hydrocarbon conversion process, such as oxygenates to olefins.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.12/477,808 filed on Jun. 3, 2009, now U.S. Pat. No. 8,268,277, and isrelated to, and claims priority to, U.S. Ser. No. 61/083,749, U.S. Ser.No. 61/083,775, U.S. Ser. No. 61/083,760, and U.S. Ser. No. 61/083,765,each filed on Jul. 25, 2008, U.S. patent application Ser. No.12/477,750, filed on Jun. 3, 2009, now U.S. Pat. No. 8,182,780, U.S.patent application Ser. No. 13/449,424, filed on Apr. 18, 2012, U.S.patent application Ser. No. 12/477,826, filed on Jun. 3, 2009, and U.S.patent application Ser. No. 12/477,700, filed on Jun. 3, 2009 andentitled, “Synthesis of Chabazite-Containing Molecular Sieves and TheirUse in the Conversion of Oxygenates to Olefins,” the entire disclosuresof each of which are hereby incorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to the synthesis of chabazite-type containingmolecular sieves and their use in the conversion of oxygenates,particularly methanol, to olefins, particularly ethylene and/orpropylene.

BACKGROUND OF THE INVENTION

The conversion of oxygenates to olefins (OTO) is currently the subjectof intense research because it has the potential for replacing thelong-standing steam cracking technology that is today theindustry-standard for producing world scale quantities of ethylene andpropylene. The very large volumes involved suggest that substantialeconomic incentives exist for alternate technologies that can deliverhigh throughputs of light olefins in a cost efficient manner. Whereassteam cracking relies on non-selective thermal reactions of naphtharange hydrocarbons at very high temperatures, OTO exploits catalytic andmicro-architectural properties of acidic molecular sieves under mildertemperature conditions to produce high yields of ethylene and propylenefrom methanol.

Current understanding of the OTO reactions suggests a complex sequencein which three major steps can be identified: (1) an induction periodleading to the formation of an active carbon pool (alkyl-aromatics), (2)alkylation-dealkylation reactions of these active intermediates leadingto products, and (3) a gradual build-up of condensed ring aromatics. OTOis therefore an inherently transient chemical transformation in whichthe catalyst is in a continuous state of change. The ability of thecatalyst to maintain high olefin yields for prolonged periods of timerelies on a delicate balance between the relative rates at which theabove processes take place. The formation of coke-like molecules is ofsingular importance because their accumulation interferes with thedesired reaction sequence in a number of ways. In particular, cokerenders the carbon pool inactive, lowers the rates of diffusion ofreactants and products, increases the potential for undesired secondaryreactions and limits catalyst life.

Over the last two decades, many catalytic materials have been identifiedas being useful for carrying out the OTO reactions. Crystallinemolecular sieves are the preferred catalysts today because theysimultaneously address the acidity and morphological requirements forthe reactions. Particularly preferred materials are eight-membered ringaluminosilicates, such as those having the chabazite (CHA) frameworktype, as well as aluminophosphates (AlPOs) and silicoaluminophosphates(SAPOs) of the CHA framework type, such as SAPO-34.

Chabazite is a naturally occurring zeolite with the approximate formulaCa₆Al₁₂Si₂₄O₇₂. Three synthetic forms of chabazite are described in“Zeolite Molecular Sieves”, by D. W. Breck, published in 1973 by JohnWiley & Sons, the complete disclosure of which is incorporated herein byspecific reference. The three synthetic forms reported by Breck areZeolite “K-G”, described in J. Chem. Soc., p. 2822 (1956), Barrer et al;Zeolite D, described in British Patent No. 868,846 (1961); and ZeoliteR, described in U.S. Pat. No. 3,030,181 (1962). Zeolite K-G zeolite hasa silica:alumina mole ratio of 2.3:1 to 4.15:1, whereas zeolites D and Rhave silica:alumina mole ratios of 4.5:1 to 4.9:1 and 3.45:1 to 3.65:1,respectively.

In U.S. Pat. No. 4,440,871, the synthesis of a wide variety of SAPOmaterials of various framework types is described with a number ofspecific examples. Also disclosed are a large number of possible organictemplates, with some specific examples. In the specific examples anumber of CHA framework type materials are described. The preparation ofSAPO-34 is reported, using tetraethylammonium hydroxide (TEAOH), orisopropylamine, or mixtures of TEAOH and dipropylamine (DPA) astemplates. Also disclosed is a specific example that utilizescyclohexylamine in the preparation of SAPO-44. Although other templatematerials are described, there are no other templates indicated as beingsuitable for preparing SAPO's of the CHA framework type.

U.S. Pat. No. 6,162,415 discloses the synthesis of asilicoaluminophosphate molecular sieve, SAPO-44, which has a CHAframework type in the presence of a directing agent comprisingcyclohexylamine or a cyclohexylammonium salt, such as cyclohexylammoniumchloride or cyclohexylammonium bromide.

Silicoaluminophosphates of the CHA framework type with low siliconcontents are particularly desirable for use in the methanol-to-olefinsprocess. Thus, Wilson, et al., Microporous and Mesoporous Materials, 29,117-126, 1999 report that it is beneficial to have lower Si content formethanol-to-olefins reaction, in particular because low Si content hasthe effect of reducing propane formation and decreasing catalystdeactivation.

U.S. Pat. No. 6,620,983 discloses a method for preparingsilicoaluminophosphate molecular sieves, and in particular low silicasilicoaluminophosphate molecular sieve having a Si/Al atomic ratio ofless than 0.5, which process comprises forming a reaction mixturecomprising a source of aluminum, a source of silicon, a source ofphosphorus, at least one organic template, at least one compound whichcomprises two or more fluorine substituents and capable of providingfluoride ions, and inducing crystallization of thesilicoaluminophosphate molecular sieve from the reaction mixture.Suitable organic templates are said to include one or more of tetraethylammonium hydroxide, tetraethyl ammonium phosphate, tetraethyl ammoniumfluoride, tetraethyl ammonium bromide, tetraethyl ammonium chloride,tetraethyl ammonium acetate, dipropylamine, isopropylamine,cyclohexylamine, morpholine, methylbutylamine, morpholine,diethanolamine, and triethylamine. In the Examples, crystallization isconducted by heating the reaction mixture to 170° C. over 18 hours andthen holding the mixture at this temperature for 18 hours to 4 days.

U.S. Pat. No. 6,793,901 discloses a method for preparing a microporoussilicoaluminophosphate molecular sieve having the CHA framework type,which process comprises (a) forming a reaction mixture comprising asource of aluminum, a source of silicon, a source of phosphorus,optionally at least one source of fluoride ions and at least onetemplate containing one or more N,N-dimethylamino moieties, (b) inducingcrystallization of the silicoaluminophosphate molecular sieve from thereaction mixture, and (c) recovering silicoaluminophosphate molecularsieve from the reaction mixture. Suitable templates are said to includeone or more of N,N-dimethylethanolamine, N,N-dimethylbutanolamine,N,N-dimethylheptanolamine, N,N-dimethylhexanolamine,N,N-dimethylethylenediamine, N,N-dimethylpropylenediamine,N,N-dimethylbutylene-diamine, N,N-dimethylheptylenediamine,N,N-dimethylhexylenediamine, or dimethyl-ethylamine,dimethylpropylamine, dimethyl-heptylamine, and dimethylhexylamine. Whenconducted in the presence of fluoride ions, the synthesis is effectivein producing low silica silicoaluminophosphate molecular sieves having aSi/Al atomic ratio of from 0.01 to 0.1. In the Examples, crystallizationis conducted by heating the reaction mixture to 170 to 180° C. for 1 to5 days.

U.S. Pat. No. 6,835,363 discloses a process for preparing microporouscrystalline silicoaluminophosphate molecular sieves of CHA frameworktype, the process comprising: (a) providing a reaction mixturecomprising a source of alumina, a source of phosphate, a source ofsilica, hydrogen fluoride and an organic template comprising one or morecompounds of formula (I):(CH₃)₂N—R—N(CH₃)₂where R is an alkyl radical of from 1 to 12 carbon atoms; (b) inducingcrystallization of silicoaluminophosphate from the reaction mixture; and(c) recovering silicoaluminophosphate molecular sieve. Suitabletemplates are said to include one or more of the group consisting of:N,N,N′,N′-tetramethyl-1,3-propane-diamine,N,N,N′,N′-tetramethyl-1,4-butanediamine,N,N,N′,N′-tetramethyl-1,3-butanediamine,N,N,N′,N′-tetramethyl-1,5-pentanediamine,N,N,N′,N′-tetramethyl-1,6-hexanediamine,N,N,N′,N′-tetramethyl-1,7-heptanediamine,N,N,N′,N′-tetramethyl-1,8-octanediamine,N,N,N′,N′-tetramethyl-1,9-nonanediamineN,N,N′,N′-tetramethyl-1,10-decanediamine,N,N,N′,N′-tetramethyl-1,11-undecanediamine andN,N,N′,N′-tetramethyl-1,12-dodecanediamine. In the Examples,crystallization is conducted by heating the reaction mixture to 120 to200° C. for 4 to 48 hours.

U.S. Pat. No. 7,247,287 discloses the synthesis ofsilicoaluminophosphate molecular sieves having the CHA framework typeemploying a directing agent having the formula:R¹R²N—R³wherein R¹ and R² are independently selected from the group consistingof alkyl groups having from 1 to 3 carbon atoms and hydroxyalkyl groupshaving from 1 to 3 carbon atoms and R³ is selected from the groupconsisting of 4- to 8-membered cycloalkyl groups, optionally substitutedby 1 to 3 alkyl groups having from 1 to 3 carbon atoms; and 4- to8-membered heterocyclic groups having from 1 to 3 heteroatoms, saidheterocyclic groups being optionally substituted by 1 to 3 alkyl groupshaving from 1 to 3 carbon atoms and the heteroatoms in said heterocyclicgroups being selected from the group consisting of O, N, and S.Preferably, the directing agent is selected fromN,N-dimethylcyclohexylamine, N,N-dimethyl-methylcyclohexylamine,N,N-dimethyl-cyclopentylamine, N,N-dimethyl-methyl-cyclopentylamine,N,N-dimethylcycloheptyl-amine, N,N-dimethyl-methylcycloheptylamine, andmost preferably is N,N-dimethyl-cyclohexylamine. The synthesis can beeffected with or without the presence of fluoride ions and, in theExamples, crystallization is conducted by heating the reaction mixtureto 180° C. for 3 to 7 days.

When any molecular sieve is used as an oxygenate conversion catalyst,three of the main economic drivers in evaluating the efficiency andprecision of the manufacturing process are the yield of the molecularsieve catalyst, the template efficiency, and the accuracy to which theacid site density of the molecular sieve product can be controlled fromthe component ingredients. In practice, even small changes in yield,template efficiency, and/or acid site density can have an enormouseffect on the economics of a commercial process, and hence there is acontinuing need to develop catalysts with improved yields, improvedtemplate efficiencies, and/or improved accuracy of acid site densitiesfor use in oxygenate conversion.

According to one aspect of the present invention, it has unexpectedlybeen found that the prime olefin selectivity (POS or total selectivityto ethylene and propylene in the product) in oxygenate conversion of CHAframework-containing aluminophosphate and silicoaluminophosphatemolecular sieves can be enhanced by increasing the crystallizationheating rate and optionally (but preferably) by increasing thecrystallization time used in their synthesis. This finding is unexpectedsince the results obtained with CHA framework type molecular sievesproduced with slower heating rates or shorter crystallization timestended to produce materials with inferior POS and/or prime olefin ratio(POR or ethylene yield divided by propylene yield) in oxygenateconversion.

According to another aspect of the present invention, it hasunexpectedly been found that the POS in oxygenate conversion of CHAframework-containing aluminophosphate and silicoaluminophosphatemolecular sieves can be enhanced by reducing the heat-up rate to thecrystallization temperature and by shortening the crystallization timeused in their synthesis. This finding is unexpected since the resultsobtained with CHA molecular sieves produced with slower heating ratesand longer crystallization times or with faster heating rates andshorter crystallization times tended to produce materials with inferiorPOS and/or POR in oxygenate conversion.

SUMMARY OF THE INVENTION

In a first aspect, the invention relates to a method of preparing asilicoaluminophosphate molecular sieve having a desired crystal size,the method comprising: (a) providing a synthesis mixture comprising asource of aluminum, a source of phosphorus, a source of silicon, and atleast one organic template containing (i) a 4- to 8-membered cycloalkylgroup, optionally substituted by 1-3 alkyl groups having from 1-3 carbonatoms, or (ii) a 4- to 8-membered heterocyclic group having from 1-3heteroatoms, said heterocyclic group being optionally substituted by 1-3alkyl groups having from 1-3 carbon atoms, and said heteroatoms in saidheterocyclic groups being selected from the group consisting of O, N,and S, wherein the synthesis mixture exhibits a Si/Al₂ ratio less than0.33; (b) inducing crystallization of a silicoaluminophosphate molecularsieve, which exhibits 90% or greater CHA framework type character, fromsaid synthesis mixture by heating said synthesis mixture at a heatingrate of more than 10° C./hr to a crystallization temperature; (c)crystallizing said silicoaluminophosphate molecular sieve at thecrystallization temperature for between 16 hours and 350 hours, suchthat a yield of silicoaluminophosphate molecular sieve greater than 8.0%is attained, wherein the crystallized silicoaluminophosphate molecularsieve exhibits a Si/Al₂ ratio less than 0.33 and has a crystal sizedistribution such that its average crystal size is not greater than 1.0μm.

In a second aspect, the invention relates to a method of convertinghydrocarbons into olefins comprising: (1) preparing asilicoaluminophosphate molecular sieve according to a method comprising:(a) providing a synthesis mixture comprising a source of aluminum, asource of phosphorus, a source of silicon, and at least one organictemplate containing (i) a 4- to 8-membered cycloalkyl group, optionallysubstituted by 1-3 alkyl groups having from 1-3 carbon atoms, or (ii) a4- to 8-membered heterocyclic group having from 1-3 heteroatoms, saidheterocyclic group being optionally substituted by 1-3 alkyl groupshaving from 1-3 carbon atoms, and said heteroatoms in said heterocyclicgroups being selected from the group consisting of O, N, and S, (b)inducing crystallization of a silicoaluminophosphate molecular sieve,which exhibits 90% or greater CHA framework type character, from saidsynthesis mixture by heating said synthesis mixture at a heating rate ofmore than 10° C./hr to a crystallization temperature; and (c)crystallizing said silicoaluminophosphate molecular sieve at thecrystallization temperature for between 16 hours and 350 hours, suchthat a yield of silicoaluminophosphate molecular sieve greater than 8.0%is attained, wherein the crystallized silicoaluminophosphate molecularsieve and the synthesis mixture both exhibit a Si/Al₂ ratio less than0.33 and the crystallized silicoaluminophosphate molecular sieve has acrystal size distribution such that its average crystal size is notgreater than 3.0 μm; (2) formulating said silicoaluminophosphatemolecular sieve, along with a binder and optionally a matrix material,into a silicoaluminophosphate molecular sieve catalyst compositioncomprising from at least 10% to about 50% molecular sieve; and (c)contacting said catalyst composition with a hydrocarbon feed underconditions sufficient to convert said hydrocarbon feed into a productcomprising predominantly one or more olefins to attain a first primeolefin selectivity of at least 70 wt %, wherein the first prime olefinselectivity is at least 1.5 wt % greater than a second prime olefinselectivity that would be attained by preparing a comparablesilicoaluminophosphate molecular sieve (i) having a crystal sizedistribution, based on the crystallized silicoaluminophosphate molecularsieve, such that its average crystal size is greater than 3.0 μm, (ii)made by heating at a rate no more than 5° C./hr up to thecrystallization temperature during the step of inducing crystallization,or (iii) both (i) and (ii).

In a third aspect, the invention relates to a method of forming anolefin-based polymer product comprising: (a) preparing a productcomprising predominantly one or more olefins according to the method ofthe second aspect of the invention; and (b) polymerizing at least one ofthe one or more olefins, optionally with one or more other comonomersand optionally in the presence of a polymerization catalyst, underconditions sufficient to form an olefin-based (co)polymer.

A fourth aspect of the invention relates to a method of convertinghydrocarbons into olefins comprising: (1) preparing asilicoaluminophosphate molecular sieve by a method comprising (a)preparing a reaction mixture comprising a source of aluminum, a sourceof phosphorus, a source of silicon, and at least one organic templatecontaining (i) a 4- to 8-membered cycloalkyl group, optionallysubstituted by 1-3 alkyl groups having from 1-3 carbon atoms, or (ii) a4- to 8-membered heterocyclic group having from 1-3 heteroatoms, saidheterocyclic group being optionally substituted by 1-3 alkyl groupshaving from 1-3 carbon atoms, and said heteroatoms in said heterocyclicgroups being selected from the group consisting of O, N, and S, (b)heating said reaction mixture at a rate of less than 10° C./hour to acrystallization temperature within the range of about 150° C. to about225° C., (c) retaining said reaction mixture within said crystallizationtemperature range for a period of less than 10 hours to inducecrystallization of a silicoaluminophosphate molecular sieve, and (d)recovering a crystallized silicoaluminophosphate molecular sieve fromthe reaction mixture; (2) formulating said silicoaluminophosphatemolecular sieve, along with a binder and optionally a matrix material,into a silicoaluminophosphate molecular sieve catalyst compositioncomprising from at least 10% to about 50% molecular sieve; and (3)contacting said catalyst composition with a hydrocarbon feed underconditions sufficient to convert said hydrocarbon feed into a productcomprising predominantly one or more olefins to attain a first primeolefin selectivity of at least 76 wt %, wherein the first prime olefinselectivity is at least 3.0 wt % greater than a second prime olefinselectivity that would be attained by contacting the hydrocarbon feedunder similar conditions with a comparable silicoaluminophosphatemolecular sieve made by heating the reaction mixture at a rate of atleast 20° C./hr up to the crystallization temperature.

A fifth aspect of the invention relates to a method of forming anolefin-based polymer product comprising: (1) preparing a productcomprising predominantly one or more olefins according to the fourthaspect of the invention; and (2) polymerizing at least one of the one ormore olefins, optionally with one or more other comonomers andoptionally in the presence of a polymerization catalyst, underconditions sufficient to form an olefin-based (co)polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an SEM micrograph of a molecular sieve made according toComparative Example A.

FIG. 2 shows an SEM micrograph of a molecular sieve made according toComparative Example B.

FIG. 3 shows an SEM micrograph of a molecular sieve made according toComparative Example C.

FIG. 4 shows an SEM micrograph of a molecular sieve made according toComparative Example D.

FIG. 5 shows an SEM micrograph of a molecular sieve made according toExample 1.

FIG. 6 shows an SEM micrograph of a molecular sieve made according toExample 2.

FIG. 7 shows an SEM micrograph of a molecular sieve made according toExample 3.

FIG. 8 shows an SEM micrograph of a molecular sieve made according toExample 4.

FIG. 9 shows an SEM micrograph of a molecular sieve made according toExample 5 and recovered after zero hours at the crystallizationtemperature (sample 5A).

FIG. 10 shows an SEM micrograph of a molecular sieve made according toExample 5 and recovered after 10 hours at the crystallizationtemperature (sample 5B).

FIG. 11 shows a graph of the MTO performance of the molecular sievesfrom Table 6.

FIG. 12 shows an SEM micrograph of a molecular sieve made according toComparative Example L.

FIG. 13 shows an SEM micrograph of a molecular sieve made according toExample 12.

FIG. 14 shows a graph of the MTO performance of the molecular sievesfrom Table 9.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Described herein is a method of synthesizing a crystallinealuminophosphate or silicoaluminophosphate containing a CHA frameworktype molecular sieve and to the use of the resultant molecular sieve asa catalyst in organic conversion reactions, especially the conversion ofoxygenates to light olefins.

In the first aspect in particular, it has been found that, by employinga relatively fast heat-up rate (typically, though not necessarily atrelatively long crystallization times) in the molecular sieve synthesis,it is possible to produce a CHA framework-type containing molecularsieve with improved POS and/or POR in oxygenate conversion.

In the fourth aspect in particular, it has been found that by employinga relatively slow heat-up rate and relatively short crystallizationtimes in the molecular sieve synthesis, it is possible to produce a CHAframework-type containing molecular sieve with improved POS and/or PORin oxygenate conversion.

In the present method, a reaction mixture is prepared comprising asource of aluminum, a source of phosphorous, at least one organicdirecting agent, and, optionally, a source of silicon. Any organicdirecting agent capable of directing the synthesis of CHA framework typemolecular sieves can be employed, but generally the directing agent is acompound having the formula (I):R¹R²N—R³  (I)wherein R¹ and R² are independently selected from the group consistingof alkyl groups having from 1 to 3 carbon atoms and hydroxyalkyl groupshaving from 1 to 3 carbon atoms and R³ is selected from the groupconsisting of 4- to 8-membered cycloalkyl groups, optionally substitutedby 1 to 3 alkyl groups having from 1 to 3 carbon atoms; and 4- to8-membered heterocyclic groups having from 1 to 3 heteroatoms, saidheterocyclic groups being optionally substituted by 1 to 3 alkyl groupshaving from 1 to 3 carbon atoms and the heteroatoms in said heterocyclicgroups being selected from the group consisting of O, N, and S.

More particularly, the organic directing agent is a compound having theformula (II):(CH₃)₂N—R³  (II)wherein R³ is a 4- to 8-membered cycloalkyl group, especially acyclohexyl group, optionally substituted by 1 to 3 methyl groups.Particular examples of suitable organic directing agents include, butare not limited to, at least one of N,N-dimethyl-cyclohexylamine,N,N-dimethyl-methylcyclohexylamine, N,N-dimethyl-cyclopentylamine,N,N-dimethyl-methylcyclopentylamine, N,N-dimethyl-cycloheptylamine, andN,N-dimethyl-methylcycloheptylamine, especiallyN,N-dimethyl-cyclohexylamine.

The sources of aluminum, phosphorus, and silicon suitable for use in thepresent synthesis method are typically those known in the art or asdescribed in the literature for the production of aluminophosphates andsilicoaluminophosphates. For example, the aluminum source may be analuminum oxide (alumina), optionally hydrated, an aluminum salt,especially a phosphate, an aluminate, or a mixture thereof. Othersources may include alumina sols or organic alumina sources, e.g.,aluminum alkoxides such as aluminum isopropoxide. A preferred source isa hydrated alumina, most preferably pseudoboehmite, which contains about75% Al₂O₃ and 25% H₂O by weight. Typically, the source of phosphorus isa phosphoric acid, especially orthophosphoric acid, although otherphosphorus sources, for example, organophosphates (e.g.,trialkylphosphates such as triethylphosphate) and aluminophosphates maybe used. When organophosphates and/or aluminophosphates are used,typically they are present collectively in a minor amount (i.e., lessthan 50% by weight of the phosphorus source) in combination with amajority (i.e., at least 50% by weight of the phosphorus source) of aninorganic phosphorus source (such as phosphoric acid). Suitable sourcesof silicon include silica, for example colloidal silica and fumedsilica, as well as organic silicon source, e.g., a tetraalkylorthosilicate.

Although, in most embodiments, the sources of silicon, phosphorus, andaluminum are the only components that form the framework of a calcinedsilicoaluminophosphate molecular sieve according to the invention, it ispossible for some small portion (e.g., typically no more than about 10wt %, preferably no more than about 5 wt %) of the silicon source can besubstituted with a source of one or more of magnesium, zinc, iron,cobalt, nickel, manganese, and chromium.

In some embodiments, the reaction mixture can have a molar compositionwithin the following ranges:

-   -   P₂O₅: Al₂O₃ from about 0.75 to about 1.25,    -   SiO₂: Al₂O₃ from about 0.01 to about 0.32,    -   H₂O: Al₂O₃ from about 25 to about 50, and    -   SDA: Al₂O₃ from about 1 to about 3,        where SDA designates the structure directing agent (template),        and wherein the molar ratios for the aluminum, phosphorus, and        silicon sources are calculated based on the oxide forms,        regardless of the form of the source added to the reaction        mixture (e.g., whether the phosphorus source is added to the        reaction mixture as phosphoric acid, H₃PO₄, or as        triethylphosphate, the molar ratio is normalized to P₂O₅ molar        equivalents).

Although the reaction mixture may also contain a source of fluorideions, it is found that the present synthesis will proceed in the absenceof fluoride ions and hence it is generally preferred to employ areaction mixture which is substantially free of fluoride ions.

Typically, the reaction mixture also contains seeds to facilitate thecrystallization process. The amount of seeds employed can vary widely,but generally the reaction mixture comprises from about 0.01 ppm byweight to about 10,000 ppm by weight, such as from about 100 ppm byweight to about 5,000 by weight, of said seeds. Generally, the seeds canbe homostructural with the desired product, that is are of a CHAframework type material, although heterostructural seeds of, forexample, an AEI, LEV, ERI, AFX, or OFF framework-type molecular sieve,or a combination or intergrowth thereof, may be used. The seeds may beadded to the reaction mixture as a suspension in a liquid medium, suchas water; in some cases, particularly where the seeds are of relativelysmall size, the suspension can be colloidal. The production of colloidalseed suspensions and their use in the synthesis of molecular sieves aredisclosed in, for example, International Publication Nos. WO 00/06493and WO 00/06494, both published on Feb. 10, 2000 and both of which areincorporated herein by reference.

In the first aspect of the invention, crystallization of the reactionmixture is carried out at either static or stirred conditions in asuitable reactor vessel, such as for example, polypropylene jars orTeflon-lined or stainless steel autoclaves. In one embodiment, thecrystallization regime can involve heating the reaction mixturerelatively quickly, at a rate of more than 10° C./hour, conveniently atleast 15° C./hour or at least 20° C./hour, for example from about 15°C./hour to about 150° C./hour or from about 20° C./hour to about 100°C./hour, to the desired crystallization temperature, typically betweenabout 50° C. and about 250° C., for example from about 150° C. to about225° C. or from about 150° C. to about 200° C., such as from about 160°C. to about 195° C. In some embodiments, however, the desiredcrystallization temperature is additionally at least 165° C., forexample at least 170° C., and can optionally also be not more than 190°C., for example not more than 185° C. or not more than 180° C. In any ofthese embodiments, when the desired crystallization temperature isreached, the crystallization can be terminated immediately or from about5 minutes to about 350 hours, and the reaction mixture can be allowed tocool; additionally or alternately, the crystallization can run for atleast about 12 hours, preferably at least about 16 hours, for example atleast 24 hours, at least 36 hours, at least 48 hours, at least 60 hours,at least 72 hours, at least 84 hours, at least 96 hours, at least 120hours, or at least 144 hours before cooling. Additionally in thisembodiment, on cooling, the crystalline product can be recovered bystandard means, such as by centrifugation or filtration, then washed anddried. Optionally, the step of inducing crystallization can be donewhile stirring.

In the fourth aspect of the invention, crystallization of the reactionmixture is carried out at either static or stirred conditions in asuitable reactor vessel, such as for example, polypropylene jars orTeflon-lined or stainless steel autoclaves. In one embodiment, thecrystallization regime can involve heating the reaction mixture slowly,at a rate of less than 8° C./hour, conveniently at least 1° C./hour,such as from about 2° C./hour to about 6° C./hour, to the desiredcrystallization temperature, typically between about 50° C. and about250° C., for example from about 150° C. to about 225° C. or from about150° C. to about 200° C., such as from about 160° C. to about 195° C. Insome embodiments, however, the desired crystallization temperature isadditionally at least 165° C., for example at least 170° C., and canoptionally also be not more than 190° C., for example not more than 185°C. or not more than 180° C. In any of these embodiments, when thedesired crystallization temperature is reached, the crystallization canbe terminated immediately (though, in some embodiments, about 5 minuteswill pass) or at least within less than 10 hours, such as less than 5hours, and the reaction mixture can be allowed to cool. Additionally inthis embodiment, on cooling, the crystalline product can be recovered bystandard means, such as by centrifugation or filtration, then washed anddried. Optionally, the step of inducing crystallization can be donewhile stirring.

In one embodiment of the first aspect of the invention, the crystallizedsilicoaluminophosphate molecular sieve has a crystal size distributionsuch that its average crystal size is less than 1.1 μm, preferably nomore than 1.0 μm, for example no more than 0.9 μm, no more than 0.8 μm,or no more than 0.7 μm. In one embodiment of the second and/or thirdaspect(s) of the invention, the crystallized silicoaluminophosphatemolecular sieve has a crystal size distribution such that its averagecrystal size is less than 3.5 μm, preferably no more than 3.0 μm, forexample no more than 2.5 μm, no more than 2.0 μm, no more than 1.5 μm,no more than 1.2 μm, no more than 1.1 μm, no more than 1.0 μm, no morethan 0.9 μm, no more than 0.8 μm, or no more than 0.7 μm. In oneembodiment of the fourth aspect of the invention, the crystallizedsilicoaluminophosphate molecular sieve has a crystal size distributionsuch that its average crystal size is less than 1.5 μm, preferably nomore than 1.2 μm, for example no more than 1.1 μm, no more than 1.0 μm,or no more than 0.9 μm.

As used herein, the term “average crystal size,” in reference to acrystal size distribution, should be understood to refer to ameasurement on a representative sample or an average of multiple samplesthat together form a representative sample. Average crystal size can bemeasured by SEM, in which case the crystal size of at least 30 crystalsmust be measured in order to obtain an average crystal size, and/oraverage crystal size can be measured by a laser light scatteringparticle size analyzer instrument, in which case the measured d₅₀ of thesample(s) can represent the average crystal size. It should also beunderstood that, while many of the crystals dealt with herein arerelatively uniform (for instance, very close to cubic, thus havinglittle difference between diameter measured along length, height, orwidth, e.g., when viewed in an SEM), the “average crystal size,” whenmeasured visually by SEM, represents the longest distance along one ofthe three-dimensional orthogonal axes (e.g., longest of length,width/diameter, and height, but not diagonal, in a cube, rectangle,parallelogram, ellipse, cylinder, frusto-cone, platelet, spheroid, orrhombus, or the like). However, the d₅₀, when measured by lightscattering in a particle size analyzer, is reported as a sphericalequivalent diameter, regardless of the shape and/or relative uniformityof shape of the crystals in each sample. In certain circumstances, thed₅₀ values measured by the particle size analyzer may not correspond,even roughly, to the average crystal size measured visually by arepresentative SEM micrograph. Often in these cases, the discrepancyrelates to an agglomeration of relatively small crystals that theparticle size analyzer interprets as a single particle. In suchcircumstances, where the d₅₀ values from the particle size analyzer andthe average crystal size from a representative SEM are significantlydifferent, the representative SEM micrograph should be the more accuratemeasure of “average crystal size.”

In a preferred embodiment, the order of addition of the components inthe mixture (i.e., in step (a)) can be important and can advantageouslybe tailored, e.g., to provide better homogeneity. For instance, step (a)can preferably comprise: (i) combining the source of phosphorus and thesource of aluminum, optionally with a liquid mixture medium, to form aprimary mixture; (ii) aging the primary mixture for an aging time andunder aging conditions (e.g., at an aging temperature), preferablysufficient to allow homogenization of the primary mixture,physico-chemical interaction between the source of phosphorus and thesource of aluminum, or both; and (iii) adding the source of silicon, theat least one organic template, and optionally additional liquid mixturemedium, to the aged primary mixture to form the synthesis mixture. Incertain cases of this embodiment, within step (iii), said source ofsilicon is combined with said primary mixture prior to adding said atleast one organic template (structure directing agent, or SDA).Advantageously, said primary mixture and said source of silicon can becombined to form a secondary mixture for a time and under conditions(e.g., temperature), preferably sufficient to allow homogenization ofthe secondary mixture, physico-chemical interaction between said sourceof silicon and said primary mixture, or both, after which said at leastone organic template is combined therewith.

When a component is added to a mixture to allow homogenization and/orphysico-chemical interaction, the aging time and temperature are two ofthe primary conditions. Although a variety of conditions can exist toallow sufficient contact for homogenization and/or interaction, in oneembodiment, when the aging temperature is somewhere between 0° C. and50° C., the aging time can advantageously be at least 5 minutes, forexample at least 10 minutes, at least 15 minutes, at least 20 minutes,at least 25 minutes, at least 30 minutes, at least 45 minutes, at least1 hour, or at least 2 hours. Again, when the aging temperature issomewhere between 0° C. and 50° C., the aging time does not really havea maximum, but can be up to 350 hours, for example up to 300 hours, upto 250 hours, up to 200 hours, up to 168 hours, up to 96 hours, up to 48hours, up to 24 hours, up to 16 hours, up to 12 hours, up to 8 hours, upto 6 hours, or up to 4 hours, depending on practical concerns relatingto synthesis timing, cost efficiency, manufacture schedules, or thelike.

Preferably, the Si/Al₂ ratio added to the synthesis mixture can be asclose as possible to the Si/Al₂ ratio of the crystallizedsilicoaluminophosphate molecular sieve (e.g., difference between theSi/Al₂ ratio in the synthesis mixture and in the crystallizedsilicoaluminophosphate molecular sieve can be no more than 0.10,preferably no more than 0.08, for example no more than 0.07) and/or thesynthesis mixture and the crystallized silicoaluminophosphate molecularsieve can both exhibit a relatively low Si/Al₂ ratio (e.g., both can beless than 0.33, preferably less than 0.30, for example no more than0.25, no more than 0.20, no more than 0.15, or no more than 0.10).

In a preferred embodiment, one or more of the following are satisfied:the source of aluminum comprises alumina; the source of phosphoruscomprises phosphoric acid; the source of silicon can include anorganosilicate comprising a tetraalkylorthosilicate; and the at leastone organic template comprises N,N-dimethylcyclohexylamine.

The product of the crystallization is an aluminophosphate orsilicoaluminophosphate containing a CHA framework-type molecular sievehaving an X-ray diffraction pattern including at least the d-spacingsshown in Table 1 below:

TABLE 1 Relative Intensities d (A) I/Io (%) 9.26 100 6.30 20 5.64 155.51 57 4.96 25 4.92 27 4.29 76 4.18 21 3.55 32 3.50 20 3.42 10 2.91 222.88 26 2.87 19

Although the crystallization product is normally a single phase CHAframework-type molecular sieve, in some cases the product may contain anintergrowth of a CHA framework-type molecular sieve with, for example anAEI framework-type molecular sieve or small amounts of other crystallinephases, such as APC and/or AFI framework-type molecular sieves. In oneembodiment, it is preferable for the crystallization product to have ashigh an amount of CHA framework type as possible, e.g., at least 95% CHAframework-type character, or even about 100% CHA framework-typecharacter (or as close as possible to single phase CHA framework-typecharacter as can currently be measured). Without being bound by theory,it is believed that silicoaluminophosphate molecular sieves havingincreased CHA framework-type character (and/or increased uniformity ofdistribution of silicon within the molecular sieve framework structure,i.e., decreased amounts of silicon islanding) can advantageously exhibitbetter performance (e.g., increased POS and optionally also POR) inoxygenates-to-olefins conversion reactions, particularly inmethanol-to-olefins conversion reactions.

As a result of the crystallization process, the recovered crystallineproduct contains within its pores at least a portion of the organicdirecting agent used in the synthesis. In a preferred embodiment,activation is performed in such a manner that the organic directingagent is removed from the molecular sieve, leaving active catalyticsites within the microporous channels of the molecular sieve open forcontact with a feedstock. The activation process is typicallyaccomplished by calcining, or essentially heating the molecular sievecomprising the template at a temperature of from about 200° C. to about800° C. in the presence of an oxygen-containing gas. In some cases, itmay be desirable to heat the molecular sieve in an environment having alow or zero oxygen concentration. This type of process can be used forpartial or complete removal of the organic directing agent from theintracrystalline pore system.

Once the crystalline product has been activated, it can be formulatedinto a catalyst composition by combination with other materials, such asbinders and/or matrix materials, which provide additional hardness orcatalytic activity to the finished catalyst.

Materials which can be blended with the present molecular sieve materialinclude a large variety of inert and catalytically active materials.These materials include compositions such as kaolin and other clays,various forms of rare earth metals, other non-zeolite catalystcomponents, zeolite catalyst components, alumina or alumina sol,titania, zirconia, quartz, silica or silica sol, and mixtures thereof.These components are also effective in reducing overall catalyst cost,acting as a thermal sink to assist in heat shielding the catalyst duringregeneration, densifying the catalyst and increasing catalyst strength.When blended with such components, the amount of present CHA-containingcrystalline material contained in the final catalyst product ranges from10 to 90 weight percent of the total catalyst, preferably 20 to 80weight percent of the total catalyst.

The CHA framework type crystalline material produced by the presentprocess can be used to dry gases and liquids; for selective molecularseparation based on size and polar properties; as an ion-exchanger; as achemical carrier; in gas chromatography; and as a catalyst in organicconversion reactions. Examples of suitable catalytic uses of the CHAframework type crystalline material described herein include (a)hydrocracking of heavy petroleum residual feedstocks, cyclic stocks andother hydrocrackate charge stocks, normally in the presence of ahydrogenation component selected from Groups 6 and 8-10 of the PeriodicTable of Elements; (b) dewaxing, including isomerization dewaxing, toselectively remove straight chain paraffins from hydrocarbon feedstockstypically boiling above 177° C., including raffinates and lubricatingoil basestocks; (c) catalytic cracking of hydrocarbon feedstocks, suchas naphthas, gas oils, and residual oils, normally in the presence of alarge pore cracking catalyst, such as zeolite Y; (d) oligomerization ofstraight and branched chain olefins having from 2-21, preferably 2-5,carbon atoms, to produce medium to heavy olefins which are useful forboth fuels, e.g., gasoline or a gasoline blending stock, and chemicals;(e) isomerization of olefins, particularly olefins having 4-6 carbonatoms, and especially normal butene to produce iso-olefins; (f)upgrading of lower alkanes, such as methane, to higher hydrocarbons,such as ethylene and benzene; (g) disproportionation of alkylaromatichydrocarbons, such as toluene, to produce dialkylaromatic hydrocarbons,such as xylenes; (h) alkylation of aromatic hydrocarbons, such asbenzene, with olefins, such as ethylene and propylene, to producealkylated aromatics, such as ethylbenzene and cumene; (i) isomerizationof dialkylaromatic hydrocarbons, such as xylenes; (j) catalyticreduction of nitrogen oxides; and (k) synthesis of monoalkylamines anddialkylamines.

In particular, the CHA framework type crystalline material produced bythe present process is useful as a catalyst in the conversion ofoxygenates to one or more olefins, particularly ethylene and propylene.As used herein, the term “oxygenates” is defined to include, but is notnecessarily limited to, aliphatic alcohols, ethers, carbonyl compounds(aldehydes, ketones, carboxylic acids, carbonates, and the like), andalso compounds containing hetero-atoms, such as, halides, mercaptans,sulfides, amines, and mixtures thereof. The aliphatic moiety willnormally contain from 1-10 carbon atoms, such as from 1-4 carbon atoms.

Representative oxygenates include lower straight chain or branchedaliphatic alcohols, their unsaturated counterparts, and their nitrogen,halogen, and sulfur analogues. Examples of suitable oxygenate compoundscan include, but are not necessarily limited to: methanol; ethanol;n-propanol; isopropanol; C₄ to C₁₀ alcohols; methyl ethyl ether;dimethyl ether; diethyl ether; di-isopropyl ether; methyl mercaptan;methyl sulfide; methyl amine; ethyl mercaptan; di-ethyl sulfide;di-ethyl amine; ethyl chloride; formaldehyde; di-methyl carbonate;di-methyl ketone; acetic acid; n-alkyl amines; n-alkyl halides; n-alkylsulfides having n-alkyl groups comprising from 3-10 carbon atoms; andthe like; and mixtures thereof. Particularly suitable oxygenatecompounds are methanol, dimethyl ether, and mixtures thereof, and mostpreferably comprise methanol. As used herein, the term “oxygenate”designates only the organic material used as the feed. The total chargeof feed to the reaction zone may contain additional compounds, such asdiluents.

In one embodiment of the oxygenate conversion process, a feedstockcomprising an organic oxygenate, optionally with one or more diluents,is contacted in the vapor phase in a reaction zone with a catalystcomprising the present molecular sieve at effective process conditionsso as to produce the desired olefins. Alternatively, the process may becarried out in a liquid or a mixed vapor/liquid phase. When the processis carried out in the liquid phase or a mixed vapor/liquid phase,different conversion rates and selectivities of feedstock-to-product mayresult depending upon the catalyst and the reaction conditions.

When present, the diluent(s) is(are) generally non-reactive to thefeedstock or molecular sieve catalyst composition and is typically usedto reduce the concentration of the oxygenate in the feedstock.Non-limiting examples of suitable diluents include helium, argon,nitrogen, carbon monoxide, carbon dioxide, water, essentiallynon-reactive paraffins (especially alkanes such as methane, ethane, andpropane), essentially non-reactive aromatic compounds, and mixturesthereof. The most preferred diluents include water and nitrogen, withwater being particularly preferred. Diluent(s) may comprise from about 1mol % to about 99 mol % of the total feed mixture.

The temperature employed in the oxygenate conversion process may varyover a wide range, such as from about 200° C. to about 1000° C., forexample from about 250° C. to about 800° C., including from about 250°C. to about 750° C., conveniently from about 300° C. to about 650° C.,typically from about 350° C. to about 600° C. and particularly fromabout 400° C. to about 600° C.

Light olefin products will form, although not necessarily in optimumamounts, at a wide range of pressures, including but not limited toautogenous pressures and pressures in the range from about 0.1 kPa toabout 10 MPa. Conveniently, the pressure can be in the range from about7 kPa to about 5 MPa, such as from about 50 kPa to about 1 MPa. Theforegoing pressures are exclusive of diluents, if any are present, andrefer to the partial pressure of the feedstock as it relates tooxygenate compounds and/or mixtures thereof. Lower and upper extremes ofpressure may adversely affect selectivity, conversion, coking rate,and/or reaction rate; however, light olefins such as ethylene and/orpropylene still may form.

In a preferred embodiment of the second aspect of the invention, themethod of converting hydrocarbons into olefins according to theinvention comprises: (1) preparing a silicoaluminophosphate molecularsieve according to the first aspect of the invention and/or a methodcomprising: (a) providing a synthesis mixture comprising a source ofaluminum, a source of phosphorus, a source of silicon, and at least oneorganic template containing (i) a 4- to 8-membered cycloalkyl group,optionally substituted by 1-3 alkyl groups having from 1-3 carbon atoms,or (ii) a 4- to 8-membered heterocyclic group having from 1-3heteroatoms, said heterocyclic group being optionally substituted by 1-3alkyl groups having from 1-3 carbon atoms, and said heteroatoms in saidheterocyclic groups being selected from the group consisting of O, N,and S, (b) inducing crystallization of a silicoaluminophosphatemolecular sieve, which exhibits 90% or greater CHA framework typecharacter, from said synthesis mixture by heating said synthesis mixtureat a heating rate of more than 10° C./hr to a crystallizationtemperature; and (c) crystallizing said silicoaluminophosphate molecularsieve at the crystallization temperature for between 16 hours and 350hours, such that a yield of silicoaluminophosphate molecular sievegreater than 8.0% is attained, wherein the crystallizedsilicoaluminophosphate molecular sieve and the synthesis mixture bothexhibit a Si/Al₂ ratio less than 0.33 and the crystallizedsilicoaluminophosphate molecular sieve has a crystal size distributionsuch that its average crystal size is not greater than 3.0 μm; (2)formulating said silicoaluminophosphate molecular sieve, along with abinder and optionally a matrix material, into a silicoaluminophosphatemolecular sieve catalyst composition comprising from at least 10% toabout 50% molecular sieve; and (c) contacting said catalyst compositionwith a hydrocarbon feed under conditions sufficient to convert saidhydrocarbon feed into a product comprising predominantly one or moreolefins to attain a first prime olefin selectivity of at least 70 wt %(as measured at about 500° C.). Advantageously, in this embodiment, thefirst prime olefin selectivity can be at least 1.5 wt % greater than asecond prime olefin selectivity (also measured at about 500° C.) thatwould be attained by preparing a comparable silicoaluminophosphatemolecular sieve (i) having a crystal size distribution, based on thecrystallized silicoaluminophosphate molecular sieve, such that itsaverage crystal size is greater than 3.0 μm, (ii) made by heating at arate no more than 5° C./hr up to the crystallization temperature duringthe step of inducing crystallization, (iii) or both (i) and (ii).Preferably, the hydrocarbon feed is an oxygenate-containing feedcomprising methanol, dimethylether, or a combination thereof, and theone or more olefins typically comprises ethylene, propylene, or acombination thereof.

In a preferred embodiment of the fourth aspect of the invention, themethod of converting hydrocarbons into olefins according to theinvention comprises: (a) preparing a silicoaluminophosphate molecularsieve according to the fourth aspect of the invention; (b) formulatingsaid silicoaluminophosphate molecular sieve, along with a binder andoptionally a matrix material, into a silicoaluminophosphate molecularsieve catalyst composition, typically comprising from at least 10% toabout 50% molecular sieve; and (c) contacting said catalyst compositionwith a hydrocarbon feed under conditions sufficient to convert saidhydrocarbon feed into a product comprising predominantly one or moreolefins, preferably to attain a first prime olefin selectivity of atleast 76 wt % (as measured at about 525° C.). Advantageously, in thisembodiment, the first prime olefin selectivity is at least 3.0 wt %greater than a second prime olefin selectivity (also as measured atabout 525° C.) that would be attained by contacting the hydrocarbon feedunder similar conditions with a comparable silicoaluminophosphatemolecular sieve made by heating the reaction mixture at a rate of atleast 20° C./hr up to the crystallization temperature. Additionally oralternately, in this embodiment, when the first and second prime olefinselectivities are measured at about 500° C., the first POS can be atleast 75 wt % and also at least 2.0 wt % greater than the second POS.Preferably, the hydrocarbon feed is an oxygenate-containing feedcomprising methanol, dimethylether, or a combination thereof, and theone or more olefins typically comprises ethylene, propylene, or acombination thereof.

A wide range of weight hourly space velocities (WHSV) for the feedstockwill function in the oxygenate conversion process. WHSV is defined asweight of feed (excluding diluents) per hour per weight of a totalreaction volume of molecular sieve catalyst (excluding inert and/orfillers). The WHSV generally should be in the range from about 0.01 hr⁻¹to about 500 hr⁻¹, such from about 0.5 hr⁻¹ to about 300 hr⁻¹, forexample from about 0.1 hr⁻¹ to about 200 hr⁻¹.

A practical embodiment of a reactor system for the oxygenate conversionprocess is a circulating fluid bed reactor with continuous regeneration.Fixed beds are generally not preferred for the process, becauseoxygenate-to-olefin conversion is a highly exothermic process thatrequires several stages with intercoolers or other cooling devices. Thereaction also results in a high pressure drop, due to the production oflow pressure, low density gas.

Because the catalyst typically needs to be regenerated frequently, thereactor should preferably allow easy removal of at least a portion ofthe catalyst to a regenerator, where the catalyst can be subjected to aregeneration medium, such as a gas comprising oxygen, for example air,to burn off coke from the catalyst, which should restore at least someof the catalyst activity. The conditions of temperature, oxygen partialpressure, and residence time in the regenerator can typically beselected to achieve a coke content on regenerated catalyst of less thanabout 1 wt %, for example less than about 0.5 wt %. At least a portionof the regenerated catalyst should be returned to the reactor.

In a preferred embodiment of the third aspect of the invention, themethod of forming an olefin-based polymer product comprises: (a)preparing a product comprising predominantly one or more olefinsaccording to the method of the second aspect of the invention; and (b)polymerizing at least one of the one or more olefins, optionally withone or more other comonomers and optionally (but preferably) in thepresence of a polymerization catalyst, under conditions sufficient toform an olefin-based (co)polymer.

In a preferred embodiment of the fifth aspect of the invention, themethod of forming an olefin-based polymer product comprises: (a)preparing a product comprising predominantly one or more olefinsaccording to the method of the fourth aspect of the invention; and (b)polymerizing at least one of the one or more olefins, optionally withone or more other comonomers and optionally (but preferably) in thepresence of a polymerization catalyst, under conditions sufficient toform an olefin-based (co)polymer.

Preferably, in either of the polymer-related aspects of the invention,the hydrocarbon feed can be an oxygenate-containing feed comprisingmethanol, dimethylether, or a combination thereof, the one or moreolefins typically can comprises ethylene, propylene, or a combinationthereof, and the olefin-based (co)polymer can be an ethylene-containing(co)polymer, a propylene-containing (co)polymer, or a copolymer,mixture, or blend thereof.

Additionally or alternately, the invention can be described by thefollowing embodiments.

Embodiment 1

A method of preparing a silicoaluminophosphate molecular sieve having adesired crystal size, the method comprising: (a) providing a synthesismixture comprising a source of aluminum, a source of phosphorus, asource of silicon, and at least one organic template containing (i) a 4-to 8-membered cycloalkyl group, optionally substituted by 1-3 alkylgroups having from 1-3 carbon atoms, or (ii) a 4- to 8-memberedheterocyclic group having from 1-3 heteroatoms, said heterocyclic groupbeing optionally substituted by 1-3 alkyl groups having from 1-3 carbonatoms, and said heteroatoms in said heterocyclic groups being selectedfrom the group consisting of O, N, and S, wherein the synthesis mixtureexhibits a Si/Al₂ ratio less than 0.33; (b) inducing crystallization ofa silicoaluminophosphate molecular sieve, which exhibits 90% or greaterCHA framework type character, from said synthesis mixture by heatingsaid synthesis mixture at a heating rate of more than 10° C./hr to acrystallization temperature; and (c) crystallizing saidsilicoaluminophosphate molecular sieve at the crystallizationtemperature for between 16 hours and 350 hours, such that a yield ofsilicoaluminophosphate molecular sieve greater than 8.0% is attained,wherein the crystallized silicoaluminophosphate molecular sieve exhibitsa Si/Al₂ ratio less than 0.33 and has a crystal size distribution suchthat its average crystal size is not greater than 1.0 μm.

Embodiment 2

A method of converting hydrocarbons into olefins comprising: (1)preparing a silicoaluminophosphate molecular sieve according to a methodcomprising: (a) providing a synthesis mixture comprising a source ofaluminum, a source of phosphorus, a source of silicon, and at least oneorganic template containing (i) a 4- to 8-membered cycloalkyl group,optionally substituted by 1-3 alkyl groups having from 1-3 carbon atoms,or (ii) a 4- to 8-membered heterocyclic group having from 1-3heteroatoms, said heterocyclic group being optionally substituted by 1-3alkyl groups having from 1-3 carbon atoms, and said heteroatoms in saidheterocyclic groups being selected from the group consisting of O, N,and S, (b) inducing crystallization of a silicoaluminophosphatemolecular sieve, which exhibits 90% or greater CHA framework typecharacter, from said synthesis mixture by heating said synthesis mixtureat a heating rate of more than 10° C./hr to a crystallizationtemperature; and (c) crystallizing said silicoaluminophosphate molecularsieve at the crystallization temperature for between 16 hours and 350hours, such that a yield of silicoaluminophosphate molecular sievegreater than 8.0% is attained, wherein the crystallizedsilicoaluminophosphate molecular sieve and the synthesis mixture bothexhibit a Si/Al₂ ratio less than 0.33 and the crystallizedsilicoaluminophosphate molecular sieve has a crystal size distributionsuch that its average crystal size is not greater than 3.0 μm; (2)formulating said silicoaluminophosphate molecular sieve, along with abinder and optionally a matrix material, into a silicoaluminophosphatemolecular sieve catalyst composition comprising from at least 10% toabout 50% molecular sieve; and (c) contacting said catalyst compositionwith a hydrocarbon feed under conditions sufficient to convert saidhydrocarbon feed into a product comprising predominantly one or moreolefins to attain a first prime olefin selectivity of at least 70 wt %,wherein the first prime olefin selectivity is at least 1.5 wt % greaterthan a second prime olefin selectivity that would be attained bypreparing a comparable silicoaluminophosphate molecular sieve (i) havinga crystal size distribution, based on the crystallizedsilicoaluminophosphate molecular sieve, such that its average crystalsize is greater than 3.0 μm, (ii) made by heating at a rate no more than5° C./hr up to the crystallization temperature during the step ofinducing crystallization, or (iii) both (i) and (ii).

Embodiment 3

A method of converting hydrocarbons into olefins comprising: (1)preparing a silicoaluminophosphate molecular sieve by a methodcomprising (a) preparing a reaction mixture comprising a source ofaluminum, a source of phosphorus, a source of silicon, and at least oneorganic template containing (i) a 4- to 8-membered cycloalkyl group,optionally substituted by 1-3 alkyl groups having from 1-3 carbon atoms,or (ii) a 4- to 8-membered heterocyclic group having from 1-3heteroatoms, said heterocyclic group being optionally substituted by 1-3alkyl groups having from 1-3 carbon atoms, and said heteroatoms in saidheterocyclic groups being selected from the group consisting of O, N,and S, (b) heating said reaction mixture at a rate of less than 10°C./hour to a crystallization temperature within the range of about 150°C. to about 225° C., (c) retaining said reaction mixture within saidcrystallization temperature range for a period of less than 10 hours toinduce crystallization of a silicoaluminophosphate molecular sieve, and(d) recovering a crystallized silicoaluminophosphate molecular sievefrom the reaction mixture; (2) formulating said silicoaluminophosphatemolecular sieve, along with a binder and optionally a matrix material,into a silicoaluminophosphate molecular sieve catalyst compositioncomprising from at least 10% to about 50% molecular sieve; and (3)contacting said catalyst composition with a hydrocarbon feed underconditions sufficient to convert said hydrocarbon feed into a productcomprising predominantly one or more olefins to attain a first primeolefin selectivity of at least 76 wt %, wherein the first prime olefinselectivity is at least 3.0 wt % greater than a second prime olefinselectivity that would be attained by contacting the hydrocarbon feedunder similar conditions with a comparable silicoaluminophosphatemolecular sieve made by heating the reaction mixture at a rate of atleast 20° C./hr up to the crystallization temperature.

Embodiment 4

The method of any of the previous embodiments, wherein the at least oneorganic template comprises N,N-dimethylcyclohexylamine.

Embodiment 5

The method of embodiment 1 or embodiment 2, wherein the heating rate instep (b) is more than 20° C./hr.

Embodiment 6

The method of embodiment 1 or embodiment 2, wherein the heating rate instep (b) is between 15° C./hr and 150° C./hr.

Embodiment 7

The method of embodiment 3 or embodiment 4, wherein the heating rate instep (b) is (i) less than 8° C./hour, (ii) at least 1° C./hour, or (iii)both (i) and (ii).

Embodiment 8

The method of any of the previous embodiments, wherein saidcrystallization temperature is between 150° C. and 200° C.

Embodiment 9

The method of any of the previous embodiments, wherein crystallizationis induced while stirring.

Embodiment 10

The method of any of embodiments 1-2, 5-6, and 8-9, wherein thecrystallized silicoaluminophosphate molecular sieve from step (c) has acrystal size distribution such that the average crystal size is lessthan 0.9 μm.

Embodiment 11

The method of any of the previous embodiments, wherein the synthesismixture and the crystallized silicoaluminophosphate molecular sieve bothexhibit a Si/Al₂ ratio less than 0.33.

Embodiment 12

The method of any of the previous embodiments, wherein step (a)comprises: (i) combining the source of phosphorus and the source ofaluminum, optionally with a liquid mixture medium, to form a primarymixture; (ii) aging the primary mixture for an aging time and underaging conditions sufficient to allow homogenization of the primarymixture, physico-chemical interaction between the source of phosphorusand the source of aluminum, or both; and (iii) adding the source ofsilicon, the at least one organic template, and optionally additionalliquid mixture medium, to the aged primary mixture to form the synthesismixture.

Embodiment 13

The method of embodiment 12, wherein, within step (iii), said source ofsilicon is combined with said primary mixture prior to adding said atleast one organic template.

Embodiment 14

The method of embodiment 12 or embodiment 13, wherein said primarymixture and said source of silicon are combined to form a secondarymixture for a time and under conditions sufficient to allowhomogenization of the secondary mixture, physico-chemical interactionbetween said source of silicon and said primary mixture, or both, afterwhich said at least one organic template is combined therewith.

Embodiment 15

The method of any of embodiments 1-3 and 5-14, wherein one or more ofthe following are satisfied: the source of aluminum comprises alumina;the source of phosphorus comprises phosphoric acid; the source ofsilicon comprises an organosilicate comprising atetraalkylorthosilicate; and the at least one organic template comprisesN,N-dimethylcyclohexylamine.

Embodiment 16

The method of any of the previous embodiments, wherein step (b) wasaccomplished using seeds having a framework type of CHA, AEI, AFX, LEV,an intergrowth thereof, or a combination thereof.

Embodiment 17

The method of any of embodiments 3-4, 7-9, and 11-16, wherein saidreaction mixture is retained within said crystallization temperaturerange for a period of less than 5 hours.

Embodiment 18

The method of any of the previous embodiments, wherein said reactionmixture is substantially free of fluoride ions.

Embodiment 19

The method of any of embodiments 2-18, wherein the hydrocarbon feed isan oxygenate-containing feed comprising methanol, dimethylether, or acombination thereof, and wherein the one or more olefins comprisesethylene, propylene, or a combination thereof.

Embodiment 20

A method of forming an olefin-based polymer product comprising: (1)preparing a product comprising predominantly one or more olefinsaccording to any of embodiments 2-19; and (2) polymerizing at least oneof the one or more olefins, optionally with one or more other comonomersand optionally in the presence of a polymerization catalyst, underconditions sufficient to form an olefin-based (co)polymer.

Embodiment 21

The method of embodiment 20, wherein the hydrocarbon feed is anoxygenate-containing feed comprising methanol, dimethylether, or acombination thereof, wherein the one or more olefins comprises ethylene,propylene, or a combination thereof, and wherein the olefin-based(co)polymer is an ethylene-containing (co)polymer, apropylene-containing (co)polymer, or a copolymer, mixture, or blendthereof.

The invention will now be more particularly described with reference tothe following Examples and the accompanying drawings.

EXAMPLES

The analysis techniques described below were among those used incharacterizing various samples from the Examples.

ICP-OES

Elemental analysis has been done using ICP-OES (Inductively CoupledPlasma-Optical Emission Spectrometry). Samples were dissolved in amixture of acids and diluted in deionized water. The instrument(Simultaneous VISTA-MPX from Varian) was calibrated using commercialavailable standards (typically at least 3 standards and a blank). Thepower used was about 1.2 kW, plasma flow about 13.5 L/min, and nebulizerpressure about 200 kPa for all lines. Results are expressed in wt % orppm by weight (wppm), and the values are recalculated to Si/Al₂ molarratios.

XRD

Either of two X-ray diffractometers was used: a STOE Stadi-P CombiTransmission XRD and a Scintag X2 Reflection XRD with optional samplerotation. Cu-K_(α) radiation was used. Typically, a step size of 0.2° 2Θand a measurement time of about 1 hour were used.

SEM

A JEOL JSM-6340F Field-Emission-Gun scanning electron microscope (SEM)was used, operating at about 2 kV and about 12 μA. Prior to measurement,samples were dispersed in ethanol, subjected to ultrasonic treatment forabout 5 to about 30 minutes, deposited on SEM sample holders, and driedat room temperature and pressure (about 20-25° C. and about 101 kPa). Ifan average particle size was determined based on the SEM micrographs,typically the measurement was performed on at least 30 crystals. In caseof the near cubic crystals, the average was based on the sizes of one ofthe edges of each crystal.

PSA

Particle size analysis was performed using a Mastersizer APA2000 fromMalvern Instruments Limited, equipped with a 4 mW laser beam, based onlaser scattering by randomly moving particles in a liquid medium. Thesamples to be measured were dispersed in water under continuousultrasonic treatment to ensure proper dispersion. The pump speed appliedwas 2000 RPM, and the stirrer speed was 800 RPM. The parameters used inthe operation procedure were: Refractive Index=1.544, Absorption=0.1.The results were calculated using the “general purpose-enhancedsensitivity” model. The results were expressed as d₅₀, meaning that 50vol % of the particles were smaller than the value. The average of atleast 2 measurements, with a delay of at least about 10 seconds, wasreported.

Comparative Example A

A synthesis mixture having a molar composition of about0.11SiO₂:P₂O₅:Al₂O₃:2 DMCHA:40H₂O, as well as 100 wt ppm seeds, wasprepared according to the following procedure. A solution of phosphoricacid was prepared by combining phosphoric acid [Acros 85%] and water. Tothis solution was added the appropriate amount of Condea Pural SB[Sasol, 75.6 wt % Al₂O₃] and the slurry was stirred for about 1 hour atabout 10° C. To this mixture was added the appropriate amount of TEOS[tetraethyorthosilicate from Aldrich]. Then the appropriate amount ofdimethylcyclohexylamine [DMCHA from Purum Fluka] was added. This mixturewas stirred for about 10 minutes before the seeds (SAPO-34 seeds) wereadded. The final mixture was transferred to an autoclave which wasstirred and heated to about 170° C. with a heat-up rate of about 5°C./hr. Immediately after reaching this temperature, the autoclave wascooled to approximately room temperature (about 20-25° C.), and thesolids were washed with demineralized water and dried at about 120° C.The yield was determined by weighing the dried solids and dividing thisweight by the weight of the initial synthesis mixture. The so-calculatedyield was about 6.6 wt %. The phase purity of the sample was determinedby X-ray diffraction and was characterized substantially by thed-spacings shown in Table 1 above. SEMs were recorded and the crystalsize was determined to be, on average, approximately 1.3 μm. The d₅₀, asdetermined by PSA, was approximately 1.2 μm.

Comparative Examples B-D

A series of samples was made according to the same procedure, but onlychanging the Si/Al₂ ratio of the synthesis mixture. All productsresulted in materials characterized substantially by the d-spacingsshown in Table 1 above, with an average crystal size around 1 μm orlarger. The d₅₀, as determined by PSA, and the yield results aresummarized in Table 2. SEM micrographs of Comparative Examples A-D areshown in FIGS. 1-4.

TABLE 2 Yield and d₅₀ [μm] of products made according to ComparativeExamples A-D with a heat-up rate of about 5° C./hr and various Si/Al₂ratios in the mixture. Compar. Ex. Si/Al₂ Yield % d₅₀ A 0.11 6.6 1.2 B0.12 7.3 1.3 C 0.13 7.5 1.0 D 0.14 7.5 0.9

Example 1

A synthesis mixture having a molar composition of about0.11SiO₂:P₂O₅:Al₂O₃:2 DMCHA:40H₂O, as well as 100 wt ppm seeds, wasprepared according to the following procedure. A solution of phosphoricacid was prepared by combining phosphoric acid [Acros 85%] and water. Tothis solution was added the appropriate amount of Condea Pural SB[Sasol, 75.6 wt % Al₂O₃] and the slurry was stirred for about 1 hour atabout 10° C. To this mixture was added the appropriate amount of TEOS[tetraethyorthosilicate from Aldrich]. Then the appropriate amount ofdimethylcyclohexylamine [DMCHA from Purum Fluka] was added. This mixturewas stirred for about 10 minutes before the seeds (SAPO-34 seeds) wereadded. The final mixture was transferred to an autoclave which wasstirred and heated to about 170° C. with a heat-up rate of about 40°C./hr, while stirring, and was kept under these conditions for about 24hours. After this time, the autoclave was cooled to approximately roomtemperature, and the solids were washed with demineralized water anddried at about 120° C. The yield was determined by weighing the driedsolids and dividing this weight by the weight of the initial synthesismixture. The so-calculated yield was about 10.5 wt %. The phase purityof the sample was determined by X-ray diffraction and was characterizedsubstantially by the d-spacings shown in Table 1 above. SEMs wererecorded and the crystal size was determined to be, on average,approximately 0.4 μm. The d₅₀, as determined by PSA, was approximately0.7 μm.

Examples 2-4

A series of samples was made according to the same procedure, but onlychanging the Si/Al₂ ratio of the synthesis mixture. All productsresulted in materials characterized substantially by the d-spacingsshown in Table 1 above, with an average crystal size of about 0.4 μm.The d₅₀, as determined by PSA, and the yield results are summarized inTable 3. SEM photographs of Examples 1-4 are shown in FIGS. 5-8.

TABLE 3 Yield and d₅₀ [μm] of products made according to Examples 1-4with a heat-up rate of about 40° C./hr and various Si/Al₂ ratios in themixture. Example Si/Al₂ Yield % d₅₀ 1 0.11 10.5 0.7 2 0.12 11.1 0.6 30.13 10.2 0.6 4 0.14 10.6 0.6

As can be seen from Tables 2-3 and FIGS. 1-8, applying the fasterheat-up rate for crystallization causes a relatively smaller averagecrystal size, even with a longer duration of heating at thecrystallization temperature (in this case, about 170° C.).

Example 5

A synthesis mixture having a molar composition of about0.05SiO₂:P₂O₅:Al₂O₃:2 DMCHA:40H₂O, as well as 100 wt ppm seeds, wasprepared according to the following procedure. A solution of phosphoricacid was prepared by combining phosphoric acid [Acros 85%] and water. Tothis solution was added the appropriate amount of Condea Pural SB[Sasol, 75.6 wt % Al₂O₃] and the slurry was stirred for about 1 hour atabout 10° C. To this mixture was added the appropriate amount of TEOS[tetraethyorthosilicate from Aldrich]. Then the appropriate amount ofdimethylcyclohexylamine [DMCHA from Purum Fluka] was added. This mixturewas stirred for about 10 minutes before the seeds (SAPO-34 seeds) wereadded. The final mixture was transferred to an autoclave which wasstirred and heated to about 170° C. with a heat-up rate of about 40°C./hr, while stirring, and was kept under these conditions for about 0hours [sample 5A] or for about 10 hrs [sample 5B]. After this time, theautoclave was cooled to approximately room temperature, and the solidswere washed with demineralized water and dried at about 120° C. Theyield was determined by weighing the dried solids and dividing thisweight by the weight of the initial synthesis mixture. The so-calculatedyield was about 1.5 wt % after about 0 hours and about 8 wt % afterabout 10 hours. SEMs were recorded and the crystal size was determinedto be, on average, approximately 0.5 μm after about 0 hours andapproximately 2 μm after about 10 hours. The crystals appear to havegrown larger during the extra time at about 170° C. The SEM pictures ofSamples 5A and 5B are shown in FIGS. 9 and 10, respectively.

Comparative Examples E-H

A series of samples was prepared having a molar composition of xSiO₂:P₂O₅:Al₂O₃:2 DMCHA:40H₂O, as well as 100 wt ppm seeds, with xvarying from about 0.02 to about 0.05, in approximately 0.01 increments.The mixtures were prepared according to the following procedure. Asolution of phosphoric acid was prepared by combining phosphoric acid[Acros 85%] and water. To this solution was added the appropriate amountof Condea Pural SB [Sasol, 75.6 wt % Al₂O₃] and the slurry was stirredfor about 10 minutes at about 10° C. To this mixture was added theappropriate amount of TEOS [tetraethyorthosilicate from Aldrich]. Thenthe appropriate amount of dimethylcyclohexylamine [DMCHA from PurumFluka] was added. This mixture was stirred for about 10 minutes beforethe seeds (SAPO-34 seeds) were added. This mixture was transferred to anautoclave which heated to about 170° C. with a heat-up rate of about 5°C./hr, while stirring, and was kept under these conditions for about 120hours. After this time, the autoclave was cooled to approximately roomtemperature, and the solids were washed with demineralized water anddried at about 120° C. The yield was determined by weighing the driedsolids and dividing this weight by the weight of the initial synthesismixture. In all cases, the phase purity of each sample was determined byX-ray diffraction and was characterized substantially by the d-spacingsshown in Table 1 above. The yield results are summarized in Table 4.

TABLE 4 Yield of products made according to Comparative Examples E-Hmade with a heat-up rate of about 5° C./hr and various Si/Al₂ ratios inthe mixture. Compar. Ex. Si/Al₂ Yield % E 0.02 15.0 F 0.03 15.1 G 0.0415.5 H 0.05 15.6

Examples 6-9

A set of mixtures with the same molar composition as in ComparativeExamples E-H was prepared, but was crystallized under slightly differentconditions. Each mixture was transferred to an autoclave which washeated to about 170° C. with a heat-up rate of about 40° C./hr, whilestirring, and was kept under these conditions for about 120 hours. Afterthis time, the autoclave was cooled to approximately room temperature,and the solids were washed with demineralized water and dried at about120° C. The yield was determined by weighing the dried solids anddividing this weight by the weight of the initial synthesis mixture. Inall cases, the phase purity of each sample was determined by X-raydiffraction and was characterized substantially by the d-spacings shownin Table 1 above. The yield results are summarized in Table 5.

TABLE 5 Yield of products made according to Examples 6-9 with a heat-uprate of about 40° C./hr and various Si/Al₂ ratios in the mixture.Example Si/Al₂ Yield % 6 0.02 8.6 7 0.03 8.2 8 0.04 8.6 9 0.05 8.7

Catalytic Evaluation of Comparative Examples E-H Versus Examples 6-9

Each sample was tested for hydrocarbon conversion performance in anautomated methanol-to-olefins (MTO) performance testing instrument. Testconditions involved addition of about 20 mg of sieve crystals calcinedfrom Comparative Examples E-H and Examples 6-9 into a ˜4 mm ID tubularreactor along with about 200 mg of silicon carbide (SiC, inert diluent).A vaporized stream of methanol was introduced at an average bedtemperature of about 500° C., a WHSV of about 100 grams MeOH per gram ofsieve per hour, and a total pressure of about 25 psig (about 273 kPag).Samples were periodically collected and analyzed by gas chromatographyfor about 20 minutes and were mathematically integrated to arrive at aconversion weighted average set of selectivities for each aged orun-aged sieve. The average combined ethylene and propylene selectivity,expressed as prime olefin selectivity (POS), are compared in Table 6below and are represented in FIG. 11.

It is noteworthy that, under these conditions, a higher heat-up rate(about 40° C./hr vs about 5° C./hr) not only results in relativelysmaller crystal size (which is preferred, in this case), but alsoattains a higher POS when used as a catalyst in MTO reactions (which isalso preferred in this case). In other words, a higher POS can beobtained with samples that are prepared from the same chemicalcomposition but that are heated at a faster rate to the crystallizationtemperature.

TABLE 6 Average prime olefin selectivity [av POS] at about 500° C. foreach sample. Example Si/Al₂ Heat-up rate av POS E 0.02  5° C./hr 64.1 F0.03  5° C./hr 67.6 G 0.04  5° C./hr 72.9 H 0.05  5° C./hr 77.1 6 0.0240° C./hr 71.6 7 0.03 40° C./hr 75.4 8 0.04 40° C./hr 76.3 9 0.05 40°C./hr 80.6

Comparative Example I

A synthesis mixture having a molar composition of about0.02SiO₂:P₂O₅:Al₂O₃:2 DMCHA:40H₂O, as well as 100 wt ppm seeds, wasprepared according to the following procedure. A solution of phosphoricacid was prepared by combining phosphoric acid [Acros 85%] and water. Tothis solution was added the appropriate amount of Condea Pural SB[Sasol, 75.6 wt % Al₂O₃] and the slurry was stirred for about 1 hour atabout 10° C. To this mixture was added the appropriate amount of TEOS[tetraethyorthosilicate from Aldrich]. Then the appropriate amount ofdimethylcyclohexylamine [DMCHA from Purum Fluka] was added. This mixturewas stirred for about 10 minutes before the seeds (SAPO-34 seeds) wereadded.

The final mixture was transferred to an autoclave which was stirred andheated to about 170° C. with a heat-up rate of about 40° C./hr. Afterabout 24 hours at this temperature, the autoclave was cooled toapproximately room temperature (about 20-25° C.), and the solids werewashed with demineralized water and dried at about 120° C. The yield wasdetermined by weighing the dried solids and dividing this weight by theweight of the initial synthesis mixture. The so-calculated yield wasabout 8.5 wt %. The phase purity of the sample was determined by X-raydiffraction and was characterized substantially by the d-spacings shownin Table 1 above. The d₅₀, as determined by PSA, was approximately 1.2μm.

Comparative Examples J-L

A series of samples was made according to the same procedure, but onlychanging the Si/Al₂ ratio of the synthesis mixture. All productsresulted in materials characterized substantially by the d-spacingsshown in Table 1 above, with an average crystal size around 1 μm orlarger. The d₅₀, as determined by PSA, and the yield results aresummarized in Table 7. An SEM micrograph of Comparative Example M isshown in FIG. 12.

TABLE 7 Yield and d₅₀ [μm] of products made according to ComparativeExamples I-L with various Si/Al₂ ratios in the mixture. Example Si/Al₂Heating rate Yield % d₅₀ I 0.02 40° C./hr 8.5 1.2 J 0.03 40° C./hr 7.91.2 K 0.04 40° C./hr 7.9 1.0 L 0.05 40° C./hr 7.9 1.1

Examples 10-13

A set of mixtures with the same molar composition as in ComparativeExamples I-L were prepared but was crystallized under slightly differentconditions. Each mixture was transferred to an autoclave which washeated to about 170° C. with a heat-up rate of about 5° C./hr, whilestirring. When the autoclaves reached about 170° C., the autoclave wascooled to approximately room temperature, and the solids were washedwith demineralized water and dried at about 120° C. The yield wasdetermined by weighing the dried solids and dividing this weight by theweight of the initial synthesis mixture. In all cases, the phase purityof each sample was determined by X-ray diffraction and was characterizedsubstantially by the d-spacings shown in Table 1 above. The results ofthe experiments are summarized in Table 8.

TABLE 8 Yield and d₅₀ [μm] of products made according to Examples 10-13with various Si/Al₂ ratios in the mixture. Example Si/Al₂ Heating rateYield % d₅₀ 10 0.02 5° C./hr 1.5 3.8 11 0.03 5° C./hr 2.2 3.9 12 0.04 5°C./hr 3.0 0.9 13 0.05 5° C./hr 3.3 0.7

The yields for Examples 10-13 were smaller than in Comparative ExamplesI-L. The d₅₀ of the materials, as determined by PSA, indicated somewhatlarger crystals. However, SEM micrographs of some of these Examplesshowed that the measured d₅₀ values were not representative for theaverage crystal size. As an example, a representative SEM micrograph ofExample 12 is shown in FIG. 13.

Example 14 Catalytic Evaluation

Each sample from Examples 10-13 and Comparative Examples I-L was testedfor hydrocarbon conversion performance in an automatedmethanol-to-olefins (MTO) performance testing instrument. Testconditions involved addition of about 20 mg of sieve crystals calcinedfrom Comparative Examples I-L and Examples 10-13 into a ˜4 mm ID tubularreactor along with about 200 mg of silicon carbide (SiC, inert diluent).A vaporized stream of methanol was introduced at an average bedtemperature of about 525° C., a WHSV of about 100 grams MeOH per gram ofsieve per hour, and a total pressure of about 25 psig (about 273 kPag).Samples were periodically collected and analyzed by gas chromatographyfor about 20 minutes and were mathematically integrated to arrive at aconversion weighted average set of selectivities for each aged orun-aged sieve. The average combined ethylene and propylene selectivity,expressed as prime olefin selectivity (POS), are compared in Table 9below and are represented in FIG. 14.

TABLE 9 Average prime olefin selectivity [av POS] at about 525° C. foreach sample. Example Si/Al₂ mixture Heating Rate, ° C./hr Average POS I0.02 40 69.7 J 0.03 40 72.3 K 0.04 40 72.9 L 0.05 40 75.5 10 0.02 5 81.911 0.03 5 80.9 12 0.04 5 80.7 13 0.05 5 79.8

As can be seen from the results in Table 9, using reaction mixtures withsimilar chemical composition, the products obtained with the slowerheat-up rate of about 5° C./hr, combined with a relatively shortcrystallization time, showed a higher POS in the oxygenates-to-olefinsreaction than the products obtained with a faster heat-up rate or with arelatively longer crystallization time.

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to variations notnecessarily illustrated herein. For this reason, then, reference shouldbe made solely to the appended claims for purposes of determining thetrue scope of the present invention.

1. A method of converting hydrocarbons into olefins comprising: (1)preparing a silicoaluminophosphate molecular sieve according to a methodcomprising: (a) providing a synthesis mixture comprising a source ofaluminum, a source of phosphorus, a source of silicon, and at least oneorganic template containing (i) a 4- to 8-membered cycloalkyl group,optionally substituted by 1-3 alkyl groups having from 1-3 carbon atoms,or (ii) a 4- to 8-membered heterocyclic group having from 1-3heteroatoms, said heterocyclic group being optionally substituted by 1-3alkyl groups having from 1-3 carbon atoms, and said heteroatoms in saidheterocyclic groups being selected from the group consisting of O, N,and S, (b) inducing crystallization of a silicoaluminophosphatemolecular sieve, which exhibits 90% or greater CHA framework typecharacter, from said synthesis mixture by heating said synthesis mixtureat a heating rate of more than 10° C./hr to a crystallizationtemperature; and (c) crystallizing said silicoaluminophosphate molecularsieve at the crystallization temperature for between 16 hours and 350hours, such that a yield of silicoaluminophosphate molecular sievegreater than 8.0% is attained, wherein the crystallizedsilicoaluminophosphate molecular sieve and the synthesis mixture bothexhibit a Si/Al₂ ratio less than 0.33 and the crystallizedsilicoaluminophosphate molecular sieve has a crystal size distributionsuch that its average crystal size is not greater than 1.0 μm, (2)formulating said silicoaluminophosphate molecular sieve, along with abinder and optionally a matrix material, into a silicoaluminophosphatemolecular sieve catalyst composition comprising from at least 10% toabout 50% molecular sieve; and (d) contacting said catalyst compositionwith a hydrocarbon feed under conditions sufficient to convert saidhydrocarbon feed into a product comprising predominantly one or moreolefins to attain a first prime olefin selectivity of at least 70 wt %,wherein the first prime olefin selectivity is at least 1.5 wt % greaterthan a second prime olefin selectivity that would be attained bypreparing a comparable silicoaluminophosphate molecular sieve (i) havinga crystal size distribution, based on the crystallizedsilicoaluminophosphate molecular sieve, such that its average crystalsize is greater than 3.0 μm, (ii) made by heating at a rate no more than5° C./hr up to the crystallization temperature during the step ofinducing crystallization, or (iii) both (i) and (ii); and wherein step(a) comprises: (i) combining the source of phosphorus and the source ofaluminum, optionally with a liquid mixture medium, to form a primarymixture; (ii) aging the primary mixture for an aging time and underaging conditions sufficient to allow homogenization of the primarymixture, physico-chemical interaction between the source of phosphorusand the source of aluminum, or both; and (iii) adding the source ofsilicon, the at least one organic template, and optionally additionalliquid mixture medium, to the aged primary mixture to form the synthesismixture, wherein said source of silicon is combined with said primarymixture prior to adding said at least one organic template.
 2. Themethod of claim 1, wherein the hydrocarbon feed is anoxygenate-containing feed comprising methanol, dimethylether, or acombination thereof, and wherein the one or more olefins comprisesethylene, propylene, or a combination thereof.
 3. A method of forming anolefin-based polymer product comprising: (a) preparing a productcomprising predominantly one or more olefins according to the method ofclaim 1; and (b) polymerizing at least one of the one or more olefins,optionally with one or more other comonomers and optionally in thepresence of a polymerization catalyst, under conditions sufficient toform an olefin-based (co)polymer.
 4. The method of claim 3, wherein thehydrocarbon feed is an oxygenate-containing feed comprising methanol,dimethylether, or a combination thereof, wherein the one or more olefinscomprises ethylene, propylene, or a combination thereof, and wherein theolefin-based (co)polymer is an ethylene-containing (co)polymer, apropylene-containing (co)polymer, or a copolymer, mixture, or blendthereof.